Perovskite-phase mixed-metal oxide materials with the general formula ABO.sub.3 may possess one or more interesting and useful electrical properties, due to the existence of polar space groups within the perovskite-phase crystals. For example, perovskites may be ferroelectric materials, which have the ability to permanently retain an electric dipole after orientation in an electric field. Perovskites may also have a pyroelectric behavior, which is exhibited by a high dependence of dielectric constant on crystal temperature. Perovskites are often piezoelectric crystals, which exhibit a charge when mechanically stressed and mechanically deform when an electric field is applied. Finally, many perovskites may be operated in a linear electric field range where they exhibit extremely high dielectric constant (generally greater than 200). As such, perovskites find application, e.g., in DRAMs, capacitors, ferroelectric devices (e.g. FRAMs), infrared detectors, and piezoelectric transducers.
The formation of perovskite-phase mixed-metal oxides as thin films (i.e. less than 5 .mu.m in thickness) on the surface of a semiconductor substrate presents particular problems. To utilize such a film for one or more of the properties listed above, the film must generally be deposited with exacting stoichiometry, high homogeneity and purity, and a controlled grain size, or the desired property may be largely non-existent. Bulk ceramic manufacture of perovskites generally meets these constraints using high temperature (typically over 1000.degree. C.) processes which are generally unacceptable for the manufacture of microelectronic device thin films. Methods of forming some perovskites in thin film form from a solution of metal-organic precursors have been developed, although these typically require annealing temperatures in excess of 600.degree. C. in order to densify, remove impurities from, and/or fully crystallize a film. Perovskite thin film deposition processes which can be used at temperatures generally less than 500.degree. C. to deposit high quality films are desired for the manufacture of microelectronic devices.